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Cutline Summer, for your next chapter at Otago

CHEM191 Summer prep course.

Get comfortable with the chemistry underneath a calculation. CHEM191 preparation in Cutline Summer starts with formulae, moles and concentration before moving into reactions and the molecules of biology.

Included in the whole Cutline Summer programme.

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Lesson previewFrom the Summer beta

Moles and concentration

How many moles of NaCl are in 250 mL of a 0.20 mol/L NaCl solution?

Find the amount of soluteThe given concentration is 0.20 moles per litre and the solution volume is 250 millilitres. Convert the volume to 0.250 litres, then multiply concentration by volume. Litre units cancel, giving 0.050 moles of NaCl.
0:360:36Silent preview
Try it yourselfA solution contains 0.050 mol of glucose in 400 mL. What is its concentration before rounding?

How to prepare for CHEM191

A useful starting point is finding the step where a calculation becomes unclear. Is it the chemical equation, the mole ratio, the unit conversion or the algebra? Revising that step is more useful than collecting another formula sheet.

  1. Make the equation mean something

    Balance a reaction and explain what its coefficients tell you about amounts in moles. Work out which reactant runs out first before calculating how much product can form.

  2. Keep quantities and units together

    Practise converting mass to moles and volume to litres. Write units beside every substitution so you can spot a concentration calculation that mixes millilitres and litres.

  3. Read a molecule before naming a reaction

    Identify charges, bonds and functional groups in a structure. Use these features to explain a property, such as an interaction with water, before learning a longer mechanism.

Try the reasoning

An introductory Cutline example, not an official exam question.

Water is added to a solution without losing any dissolved solute. What happens to its concentration?

Show the explanation

The concentration decreases. The amount of solute stays the same while the solution volume increases. In concentration = amount of solute / volume of solution, the denominator has increased.

Explain which quantity changes and which stays fixed before substituting values into an equation.

What the CHEM191 Summer course will cover

Realistic chemistry exam-style questions, with the calculations and chemical reasoning worked step by step.

Planned Cutline Summer modules. These describe our preparation scope, not an official university course outline or a claim that every assessment is covered.

  1. Module 1

    Maths toolkit

    Calculator moves for CHEM191: mL to L, powers of ten, log and 10ˣ for pH, and ln for half-life.

    Practise applying it: Move between [H₃O⁺] and pH with log and 10ˣ, and use ln to find a time from a first-order decay.

  2. Module 2

    Headstart

    Reading the periodic table, polar bonds and Lewis structures, then moles, limiting reactants and concentration, the stoichiometry that opens every CHEM191 progress test.

    Practise applying it: Use a balanced equation to identify the limiting reactant and calculate the product amount.

  3. Module 3

    Water, solutions and equilibrium

    Hydrogen bonding, solubility, electrolytes, reaction quotients, equilibrium calculations, changing mixtures and precipitation.

    Practise applying it: Compare the reaction quotient with the equilibrium constant to predict how a mixture changes.

  4. Module 4

    Acids, bases and buffers

    Conjugate pairs, pH, strong and weak acids, buffers, titration curves and molecular ionisation.

    Practise applying it: Choose an acid-base model and calculate pH from the information in the question.

  5. Module 5

    Energy and equilibrium

    Heat, enthalpy, Hess’s law, entropy, Gibbs energy, temperature, reaction coupling and equilibrium constants.

    Practise applying it: Use Gibbs energy to judge reaction direction under the stated conditions.

  6. Module 6

    Reaction rates

    Rate laws, initial rates, first-order reactions, half-life, reaction mechanisms, activation energy and temperature.

    Practise applying it: Infer a rate law from experimental data and explain how temperature affects the rate.

  7. Module 7

    Redox and coordination

    Oxidation states, half-equations, electrochemical cells, electrode potentials, membrane potentials, metal ions and biological electron transfer.

    Practise applying it: Balance a redox reaction and use electrode potentials to judge its direction.

  8. Module 8

    Molecular structure

    Orbitals, Lewis structures, formal charge, resonance, molecular shape, functional groups, isomers and stereochemistry.

    Practise applying it: Draw a Lewis structure and justify formal charges, molecular shape or an isomer assignment.

  9. Module 9

    Organic reaction mechanisms

    Electron movement, nucleophiles, bases, leaving groups, substitution, elimination and addition reactions of alkenes.

    Practise applying it: Follow electron movement to predict a product and justify the reaction mechanism.

  10. Module 10

    Carbonyls and carbohydrates

    Alcohols, amines, carbonyl reactions, imines, acetals, sugar rings, reducing sugars, glycosidic bonds and polysaccharides.

    Practise applying it: Read a sugar structure and identify whether it has a reducing end.

  11. Module 11

    Lipids, amino acids and proteins

    Carboxylic acid derivatives, esters, lipids, amino acid charge, peptides, protein structure and protease action.

    Practise applying it: Determine an amino acid’s charge at a stated pH and explain your reasoning.

  12. Module 12

    Aromatic compounds and nucleic acids

    Aromatic rings, heterocycles, nucleosides, nucleotides, phosphate bonds, base pairing and nucleic-acid stability.

    Practise applying it: Use molecular structure to explain base pairing and the stability of a nucleic acid.

Part of Cutline Summer.

One programme covering CELS191, CHEM191, PHSI191 and HUBS191. Choose Cutline Summer for the summer, or Summer + Cutline HSFY 2027 to carry on through every HSFY paper in 2027. The Summer Mentor Circle (Nov to Feb only) is by offer from the application.

Short lessons, tutor walkthroughs and exam-style practice are planned for Summer. Try a beta lesson to see the approach while the full programme is being built.

Summer Mentor Circle, 50 places

Summer + Cutline HSFY 2027 + Summer Mentor Circle

NZ$1,949or $650 + $650 + $649

Chosen on suitability from the application.

HSFY Head Start Accelerator

Cutline Summer

NZ$699or 3 x $233

Programme access 16 November 2026 to 28 February 2027.

Prices are in NZD and include GST. These are whole-programme plans, not separate paper purchases. Full refund within 14 days of paying, and the first module guarantee to 31 December 2026.

Questions about CHEM191 preparation

What if I have little chemistry background?

Start with formulae, balancing equations and moles. Also check Otago’s preparation guidance: it describes CHEM150, Introductory Chemistry and pathway options, each with its own eligibility. Cutline Summer is independent preparation and does not replace those university options or their practical requirements.

Is this different from the CHEM191 question bank?

Yes. Summer is preparation before the year begins. If you are already taking the paper, visit CHEM191 practice questions for the in-year practice options.

For official paper information, see Otago’s CHEM191 page and its HSFY preparation guidance.

Explore the other Summer papers

Read the HSFY summer preparation guide

Take the free plan and guide with you

A plan around your own exams and summer, plus the guide. Both free.

Get the free HSFY plan and guide

Free. No card. One tap in the email to confirm. If you do not confirm, we keep your address for up to 7 days to send two reminders, then delete it.

CHEM191 summer prep course | Cutline